PC Crashes for no reason that I can find

Hi guys,

My PC at work keep crashing for absolutley no reason from what I can tell.
There is no certain time as to when it crashes, it is at random. None of the components are under any stress and are overheating as I have checked all the tempretures and even ran stress tests to ensure that all the hardware is working as it should.
I have tested the RAM, CPU and GPU, all of which report back with no problems whatsoever.
I have ran a test on the hard drive using Seagate tools and windows own chkdsk, both of which again report back no errors.

I have tried swapping the RAM into different DIMM slots to make sure the slots work, I have changed the sata cables and changed the ports that they are plugged in to.
I have changed the ports that the PSU cables are plugged into on the actual PSU itself ( didn't explain that very well ) and still crashes.

The event log reports bad sectors in the hard drive but nothing else which confuses me as chkdsk doesn't find anything at all.

I have also tried re-imaging the machine but still nothing, I have re-imaged it four times now.

There are five of us in the office, and four of us all have the exact same PC specs, yet I have the only one that crashes, there are no bios updates either.

My system spec is as follows:

Intel Core i7
8GB DDR3 RAM
Nvidia geforce 210
Samsung 1TB HDD
850W PSU
Windows 7 professional 64 bit


has anyone got any ideas?

thanks
Edited by fleXx - 6/1/12 at 6:06am

Nah they would'nt they're too old for that now I would hope lol, and they're all plugged in fine, another problem im facing with now is it crashes on the bios splash screen?
Now sometimes it doesn't and then I can boot but at the minute I cannot log on as it keeps crashing at the slash screen.

Yes I have ran memtest, but only for one pass as I didnt have time to let it run for much longer, ill run it again tonight and let it work through until monday and see if it comes up with any errors then.
When you say let it run for a couple of hours, do you mean litrally just run? or do you mean with some sort of test running?

I sometimes get BSoD's but I think that's due to the crashes I've had in the OS in the first place, those crashes have no error messages or blue screens, the PC just freezes and will not move.
At the minute im trying to re-install windows again, but its crashed yet again at the bios splash screen and even when it gets past it, the disk only gets so far before the system crashes again.
At least I think it crashes it might be just the disk loading at a very very slow pace, but the disk is fine because we have a couple of windows 7 disks and they all do the same thing, just do not load for such a long time that you just give up trying.

About 18 months old so I can't imagine they could break in such a short time period? and i'll check the voltages now, but I don't think it could be those either because the technicians I work with don't touch the voltages for any of the components.